1. Field of the Invention
This invention relates to the field of illumination, and in particular to a universal safety light in which illumination is provided by an electro-luminescent (EL) lighting element, and which includes a partially transparent housing arrangement containing the electro-luminescent lighting element and all necessary power supply and control circuitry.
2. Discussion of Related Art
While electro-luminescent lighting arrangements have been proposed for use in a variety of specific contexts relating to safety, including illumination of footwear, headwear, backpacks, safety guides, moving objects, and even flying objects, most of the previous proposals have involved separate illumination and power supply/control arrangements. The present invention relates to a self-contained universal safety light that can be used in a variety of applications, and which represents an improvement over both conventional safety light arrangements of the type utilizing LEDs and incandescent lights, and also over previous electro-luminescent lighting arrangements.
The advantages of electro-luminescent lighting relative to incandescent light are well-known, including both increased durability and flexibility. In addition, electro-luminescent lighting arrangements have a number of advantages over light emitting diode (LED) lighting arrangements, including color choice and brightness (the brightest LEDs are red, which can generally only be used for emergency lighting), increased viewing angle, flexibility, low power consumption, and the ability to be printed with designs for an attractive daytime appearance. In addition, electro-luminescent lighting elements can be arranged to exhibit special effects such as flashing in a variety of patterns.
In addition, electro-luminescent lighting elements can now be arranged as three-dimensional electro-luminescent fibers or tubes, often provided as "do-it-yourself" lighting kits, with changeable colors and a 360.degree. viewing angle, the fibers or tubes changing color in response to a sensor for controlling the voltage or frequency of the electrical trigger current supplied to the electro-luminescent element for an exceptionally attractive lighting display.
Even though the improvement in visibility and attractiveness of electro-luminescent lights in comparison with ordinary LED warning lights, such as the ones described in U.S. Pat. Nos. 5,463,537 and 5,371,662, and even the improved LED shoe module described in copending U.S. Patent application Ser. No. 08/517,502, is immediately apparent, however, problems in implementation have prevented widespread use of electro-luminescent lighting elements in most applications.
Despite the advantages of electro-luminescent lighting elements, substitution of electro-luminescent lighting elements for LEDs is not simply a matter of design choice, given the different electrical requirements and structures of LEDs and electro-luminescent light elements. From an electrical standpoint, for example, while LEDs can utilize either DC power or relatively low frequency pulses, electro-luminescent lighting arrangements require high frequency AC power supplies. Converting the output of a DC power source to the frequencies and voltages necessary to trigger an electro-luminescent lighting element involves either high labor cost traditional analog circuitry, or relatively expensive integrated circuits, and it is difficult to fit such circuitry into limited spaces such as might be available in the heel of a shoe, a bicycle warning light, or a flashlight.
Conventional electrical circuit arrangements for powering LEDS, such as described in U.S. Pat. Nos. 5,175,528, 5,313,187, and 5,313,188, which provide a square wave output for maximizing the efficiency of LEDs, do not provide a practical means for powering an electro-luminescent lighting arrangement, and conventional circuitry specifically designed for electro-luminescent lighting arrangements have tended to be expensive and difficult to implement in contexts where cost and space are considerations, such as in a safety light of the type with which the present invention is concerned.
The basic approach of the present invention is therefore to provide a safety light in which LEDs are replaced by electro-luminescent lighting elements, which may be conventional electro-luminescent lighting elements or three-dimensional electro-luminescent fibers, but in which the electro-luminescent lighting elements are arranged in a novel and especially efficient manner. The starting point is the LED lighting module described in U.S. Patent application Ser. No. 08/517,502 now U.S. Pat. No. 5,599,088, which itself offers a number of improvements over conventional flasher modules, including power supply arrangement, but which suffers from the limited color choice (basically, red) and narrow viewing angle of traditional LED arrangements. Instead of directly substituting electro-luminescent lighting elements, including strips, tubes, panels, and three-dimensional fibers for LEDs in the lighting module of the copending application, however, the present invention makes a number of modifications to the prior module in order to make the substitution possible in a commercially viable manner, and which enables use in a wide variety of applications (which is why the invention is referred to as a "universal" safety light).